Fructose is a simple sugar. The metabolism of fructose in the human body is different from that of sucrose in that it does not involve insulin, with the result that fructose is widely used as a sugar for diabetics. Moreover, as is known, fructose is capable of quickly and abundantly producing glycogen, which has a liver-protective activity; for this reason the use of fructose is also advisable in the diets of people with liver complaints and for the elderly. Yet again, the sweetening power of fructose is greater than that of sucrose, so that its use in food products instead of sucrose reduces the carbohydrate content of the food. Finally, it is known that fructose is less carciogenic than sucrose. The present tendency to replace sucrose by fructose in various food products, particularly in baked products, is therefore readily understandable.
In practice, fructose is available in two forms: that of a syrup, with a concentration of 70% by weight, and in the crystalline form. The syrup is convenient in that it is noticeably less expensive than crystalline fructose. In addition the syrup is convenient from the technological point of view, in that it is easy to store, may be metered volumetrically without difficulty for feeding to the production line, and distributes itself uniformly in the dough without giving rise to complications. However, in addition to fructose, it also contains other substances, principally glucose, the presence of which (tolerated until now) is undesirable. Crystalline fructose has the advantage of being practically pure. However, because of its hygroscopic nature, storage and metering of crystalline fructose in a food production factory are generally considered as hardly practicable. Furthermore, during the preparation and kneading of the dough, crystalline fructose readily gives rise to the formation of lumps which render the kneading difficult, and furthermore, the dough is very sticky. Lumps formation and stickiness can be reduced only by prolonged kneading but on the other hand it is known that with kneading prolonged beyond a certain limit, the quality of the dough and of the final product deteriorate. Therefore, the use of crystalline fructose in the production of baked products was rather problematic until now.
A further problem connected with the use of fructose (both in the crystalline and in the syrup form) in the production of baked products lies in the considerable browning of the product during baking at the temperatures usual for other products, generally from 230.degree. C. to 280.degree. C. According to the known art, the browning may be reduced by lowering the baking temperature and/or by shortening the baking time. This implies that the proportion of water in the dough must necessarily be reduced to the minimum absolutely necessary since, otherwise, the moisture content in the baked, finished product would be intolerably high. Preferably, according to the known art, turbulence ovens or high-frequency ovens should be used for baking.
Under these circumstances, the baked products made until now on a commercial scale, which are preservable and include fructose as the sweetener instead of sucrose, consist of crisp or crumbly biscuits having a moisture content of less than 5% by weight and obtained with the use of fructose syrup.